Preimplantation genetic testing using Karyomapping for a paternally inherited reciprocal translocation: a case study

Preimplantation genetic testing (PGT) using Karyomapping is used to screen embryos for single gene disorders prior to implantation. While Karyomapping is not designed to screen for abnormalities in chromosome copy number, this testing is based upon a genome-wide analysis of single nucleotide polymorphisms (SNP) and, as such, some chromosome abnormalities are detected. The aim of this study was to validate whether Karyomapping could provide reliable and accurate PGT for a paternal 46,XY,t(10;19)(p15;p13.3) reciprocal translocation.

Feasibility/validation for PGT was performed using DNA from the couple, as well as DNA from the paternal parents and from a previous unbalanced pregnancy. Karyomapping was performed using Illumina's HumanKaryomap-12 BeadChip microarray technology. SNP analysis was performed using BlueFuse Multi software (Illumina). Transmission of the translocation was assessed through the analysis of SNP markers on the chromosome regions of interest.

PGT-SR was determined to be feasible as chromosomal SNP analysis could reliably distinguish normal/balanced outcomes from all unbalanced outcomes. The couple transferred a normal/balanced embryo in an elective single embryo transfer procedure following 2 IVF/PGT-SR cycles. A clinical pregnancy was achieved.

This is the first report of PGT-SR test validation using Karyomapping for a 46,XY,t(10;19)(p15;p13.3) reciprocal translocation. Karyomapping may offer a means of detecting unbalanced forms of chromosome rearrangements when other PGT platforms fail.